Networks typically connect a number of workstations. Networks can be linked together by a bridge. When a workstation wishes to transmit information to another workstation in the same network, it can transmit the information directly without going through a bridge. However, a bridge must be used when a workstation in one network wishes to transmit information to a work station in another network.
As the number of workstations within a network increases so does the volume of transmission traffic within the network and between networks. To minimize the volume of transmission traffic, a prior bridge may be used. The prior bridge minimizes transmission traffic between the linked networks by monitoring all transmissions and passing through only those transmissions between workstations of different networks. To accomplish this, the prior bridge maintains a list of workstation addresses, which the prior bridge checks every time it receives a transmission. One method of checking the workstation address list is a sequential comparison of each workstation address in the list with the destination address of the transmission. Another and faster method of checking the workstation address list is a parallel comparison of workstation addresses using a content addressable memory (CAM). The (CAM) simultaneously checks the transmission address against all workstation addresses it stores.
One prior CAM includes a CAM array, an internal controller and a set of registers, as shown in FIG. 1. The prior CAM includes a single port for accessing the CAM. The external arbiter arbitrates access to that port by the network and the bridge processor, which maintains the list of workstation addresses stored within the CAM. The external arbiter gives the network priority access to the CAM port because the network cannot postpone its transmission. If the bridge processor and network seek access to the CAM port at the same time, the external arbiter denies the bridge processor access. The external arbiter also denies the bridge processor access to the CAM port if the network already has access to the CAM port. Additionally, if the bridge processor is in the process of loading its registers and the network seeks access, the external arbiter interrupts the bridge processors access. Because the prior CAM includes only one set of registers, interruption causes the information written into the registers by the bridge processor to be overwritten by the network. As a result, the bridge processor must reload the registers when it regains access to the CAM port. This decreases bridge performance.